To determine how well stabples can satisfy energy and protein needs of infants who are: 1) healthy, 2) convalescing from malnutrition, 3) recovering from diarrhea, or 4) severely malnourished. Limitations to intake imposed by: a) bulkiness, b) carbohydrate and protein digestibility, c) protein content and quality, and d) effect on absorption of dietary fat. Wheat, as pasta, and white potato, boiled and oven-dried, will be studied independently, by balance technique, in diets of 9 healthy 4-month old and 9 convalescent malnourished 6-24 month old infants; 6.4% of diet calories as protein and 25% as 20-80 mix of cottonseed-soy oils. Staple to provide approximately 75, 50 and 25% of calories and 100, 67, and 33% of protein in pre-ordered varied sequence during 9-day periods, each preceded and followed by 9-day period without staple. In all, casein to provide balance of protein and sucrose balance of carbohydrate. Time required to feed diets; stool wet and dry weight, fat, nitrogen and energy (bomb calorimetry); urine nitrogen will be measured. Plasma free amino acids in fasting state and 3 and 4 hours postprandially for each diet. Maximal proportions tolerated and utilized will be fed to 4 convalescent infants for 90 plus days to study growth and digestive adaptability, to 6 infants recovering from diarrhea, and 6 severely malnourished but not acutely ill. Metabolic collections to study digestibility and utilization in these situations.